This is an application for a K23 award for Dr. Jennifer Ho, a cardiology research fellow at Massachusetts General Hospital, Boston. Dr. Ho is establishing a career in patient-oriented clinical research in cardiac remodeling and heart failure The K23 award will enable Dr. Ho to accomplish the following training goals critical to her future career: (1) to continue her training in advanced biostatistical methods; (2) to gain expertise in advanced noninvasive cardiac and vascular imaging; (3) to become facile with patient-oriented intervention studies in cardiovascular physiology; and (4) to establish an independent clinical research career. In order to achieve these goals, Dr. Ho will work closely with her mentoring team, consisting of her primary mentor, Dr. Thomas Wang, Director of the Program in Human Cardiovascular Physiology and Metabolism at Massachusetts General Hospital, and her two co-mentors, Dr. Daniel Levy, Director of the Framingham Heart Study, and Dr. Carolyn Ho, an expert in noninvasive cardiovascular imaging and genetic cardiomyopathies. Dr. Ho's long-term goals are to define subclinical disease phenotypes that lead to overt heart failure using informative biomarkers and non-invasive imaging, allowing the identification and potential treatment of at-risk individuals with therapies targeted at the underlying pathophysiology. Her proposed research will focus on one such potential pathway, Galectin-3. Experimental evidence suggests that Galectin-3 is an important mediator of cardiac fibrosis, an important contributor to the pathophysiology of heart failure. As a biomarker, Galectin-3 also predicts prognosis in patients with heart failure. Preliminary data shows Galectin-3 to predict incident heart failure events in the community. Dr. Ho's research will focus on elucidating the relation of Galectin-3 to subclinical cardiovascular phenotypes that precede overt heart failure. Specifically, she will study the relation to ventricular and vascular function in the community (Aim 1), and the relation of Galectin-3 to cardiac phenotypes in hypertrophic cardiomyopathy, a condition marked by cardiac fibrosis (Aim 2). Lastly, Dr. Ho will conduct a pilot randomized placebo-controlled trial t study the effect of Galectin-3 inhibition on collagen metabolism and subclinical cardiovascular phenotypes in hypertensive individuals with elevated Galectin-3 levels (Aim 3). This research and training plan will form the basis of a biomarker-guided targeted therapy trial in an at-risk population, to be proposed in an R01 grant application before the end of the K23 award.